Venom from southern copperhead snake ( Agkistrodon contortrix contortrix). II. A unique phospholipase A 2 that induces platelet aggregation

Abstract

J. Takagi, F. Sekiya, K. Kasahara, Y. Inada and Y. Saito. Venom from southern copperhead snake ( Agkistrodon contortrix contortrix). II. A unique phospholipase A 2 that induces platelet aggregation. Toxicon 26, 199 – 206, 1988. — A platelet aggregation factor was purified from the venom of southern copperhead snake ( Agkistrodon controtrix contortrix) by DEAE-cellulose ionexchange chromatography, precipitation with ammonium sulfate, affinity chromatography using bovine serum albumin as ligand, and gel filtration on Cellulofine GCL-2000. It had molecular weights of 11,000 and 14,000, as determined by gel filtration chromatography and sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDS - PAGE), respectively. It consists of a single polypeptide, and was identified as a phospholipase A 2. It was quite resistant to heat and various denaturing reagents including urea and SDS. It lost both phospholipase A 2 activity and platelet aggregating activity upon modification of histidine residue(s) with p-bromophenacyl bromide. Its specificity towards the β-position of phospholipid in esterolytic reaction was confirmed by gas - liquid chromatography using a pure synthetic phosphatidylcholine. Platelet aggregation by this phospholipase A 2 was completely inhibited by prostacyclin, but was little inhibited by aspirin which indicates almost no direct participation of released arachidonic acid in the aggregation mechanism.